Intentionally mismatched bat's in dual system?

[Mobryan]

I'm going to a backup battery system using eveldaves $50 cookbook thread, probably sometime this summer. I plan on having the tie-in solenoid manually switched. Charging for now is a locally rebuilt 60amp Delco 10si with the voltage sensor wire(I forget the technical term) at the primary battery. Eventually I'll go to a fully independent dual bat dual alt system, but that's down the road a ways. My primary battery is going to be the DieHard Platinum 31M Marine combo. Since the second battery will have no routine loads on it, is there a problem with using a substantially smaller (read lighter/cheaper) battery for the backup position? Can I mix AGM/flooded in this application, and/or is there a good compact AGM for that use? Basically all it need to do is crank over my V-8 on the off chance I drain the primary. The wiring is such that I can swap cables to make the smaller battery the system primary if the DHP tanks, so I could start on the secondary, then charge the primary once I'm running.

Any other thoughts/comments/pitfalls I should know about?

Thanks


Matt

 

[dwh]

Most all flooded and AGM are rated about the same as regards charging specs, so yes, you can mix and match types and sizes of flooded and AGM. They'll both eventually get charged up to whatever voltage your voltage regulator is set to. (You *can not* mix GEL type with anything else though.)

You can't mix and match batteries if they are tied into a *permanent* battery bank, or if they are being charged with a multi-stage charger (i.e., a charger with a constant current bulk stage or an absorb stage).

But if they are only tied while there is charging going on, and it's just a normal alternator/voltage regulator, it won't be a problem.

 

[Mobryan]

Thanks.


Matt